The present invention pertains to an exhaust cleaning system for motor vehicles, especially a diesel exhaust cleaning system for medium to heavy utility vehicles, with an exhaust muffler, catalytic converter and exhaust gas particle filter element.
Diesel exhaust cleaning systems for utility vehicles of the above-mentioned type, in which the catalytic converter, the exhaust gas particle filter element, and one or more exhaust mufflers are arranged in the exhaust line of the utility vehicle behind the diesel engine, have been known according to the state of the art. The functions for muffling, HC/NOx reduction as well as soot particle reduction are assumed by individual, separate components of the exhaust system. The individual components require a relatively large space for mounting. In addition, depending on the weathering conditions, the individual components are subject to varying thermal stress and corrosion-promoting conditions, which compromise the service life. In addition, the mounting of the exhaust system is difficult.
Based on the above-mentioned general state of the art, the object of the present invention is to provide an exhaust cleaning system of the type mentioned in the introduction, which is characterized by an especially compact design and nevertheless efficiently and reliably assumes the functions of sound muffling, HC/NOx reduction and particle reduction with simple means.
According to the invention, an exhaust cleaning system is provided for motor vehicles, especially a diesel exhaust cleaning system for medium to heavy utility vehicles, with exhaust muffler, catalytic converter and exhaust gas particle filter element. The exhaust muffler, the exhaust gas particle filter element, and the catalytic converter are integrated in a common housing and form a structural, functional unit.
The exhaust muffler of a multichamber design with at least one baffle chamber and at least one absorption chamber in a common housing advantageously has an outerjacket with an oval to rectangular cross section and flat front-side axial ends, wherein the baffle chamber(s) and the absorption chamber(s) are separated from one another by at least one radial partition.
The catalytic converter is preferably an SCR catalytic converter for the selective catalytic reduction of the harmful substances present in the exhaust gas.
The exhaust gas particle filter element is preferably a diesel particle filter element.
In particular, the SCR catalytic converter, the diesel particle filter element, and a U-shaped tubular urea injection element are provided in the housing in the axial direction, extending over the chambers and essentially in parallel to one another.
In a special variant, the housing is divided by at least three radial partitions located at spaced locations from one another into at least four chambers, wherein the first partition between the first chamber and the second chamber, the second partition between the second chamber and the third chamber, as well as the third partition between the third chamber and the fourth chamber have passage openings for the fastened mounting of the SCR catalytic converter, the diesel particle filter element as well as the U-shaped tubular element.
The diesel particle filter element advantageously comprises a connection flange, to which a diesel burner is detachably fastened on the outside of the housing, wherein the connection flange is located and fastened in the plane of the first front-side axial end of the housing, which axial end is associated with the first chamber and limits the first chamber together with the first partition in the axial direction.
In the area of the other, second front-side axial end of the housing, the diesel particle filter element may have a conical cleaning bell with a blind plug that can be opened at the tapered end of the cleaning bell, the tapered end of the cleaning bell including the blind plug being located in the plane of the second front-side axial end of the housing.
Furthermore, the diesel particle filter element may have a first jacket perforation or opening in the area of the third chamber for the radially outwardly directed passage of the exhaust gas.
The diesel particle filter element preferably has a radial exhaust gas inlet in the area of the first chamber, an exhaust gas inlet pipe being provided on the housing jacket side.
With reference to the urea injection, the exhaust cleaning system comprises especially a U-shaped tubular element with a short straight tube section with an axial exhaust gas inlet in the area of the third chamber and a longer straight tube section with an axial exhaust gas outlet in the area of the fourth chamber, as well as a 180xc2x0 elbow section in the area of the first chamber, wherein a straight urea feed pipe aligned with the axis of the longer tube section opens into the 180xc2x0 elbow section approximately in the extension of the above-mentioned axis of the longer tube section, and the elbow section extends at least to the first axial end of the housing.
The short and long straight tube sections extend especially in parallel to one another at the same level of the housing.
The shorter straight tube section may have a jacket perforation in the area of the second chamber.
The SCR catalytic converter preferably comprises an axially directed, hollow exhaust gas outlet housing part in the area of the first chamber, while the catalytic converter core is located in the area of the fourth, third and second chambers.
In the area of the first chamber, the exhaust gas outlet housing part of the catalytic converter preferably has a jacket-side exhaust gas outlet opening, to which a tube elbow is connected, which leads to the first axial end of the housing and forms the exhaust gas outlet of the exhaust muffler.
The hollow exhaust gas outlet housing part may have a jacket perforation and a front-side perforation in the area of the first front-side axial end.
The housing of the catalytic converter core is preferably provided with stiffening beads.
The SCR catalytic converter comprises a box-shaped housing in a variant having a simple design.
In an especially advantageous variant of the present invention, the SCR catalytic converter and the diesel particle filter element as well as the U-shaped tubular element are embedded in an absorption material in the area of the first and second chambers and the first and second chambers are thus designed as absorption chambers, while the third and fourth chambers are baffle chambers.
A fifth chamber, which is arranged downstream of the fourth chamber, is designed as an absorption chamber and contains a muffler absorption material, is preferably provided at the second front-side axial end of the housing, and the fourth partition has perforations.
A compact system with the integrated functional modules muffling, NOx reduction and particle reduction is created by the present invention with minimal volume and at low manufacturing costs. The compact system is especially suitable for medium to heavy diesel-powered utility vehicles. The compact system also meets more stringent emission regulations.
In conjunction with the muffling of the exhaust noise, the reduction of the three functional components to a single functional component is performed in a combined system.
The compact system for the aftertreatment of the pollutant components HC/NOx/particles and muffling is characterized especially by
muffing/NOx reduction/particle reduction by the integration of the three functional elements in a single housing with minimal volume,
a diesel particle filter element with integrated diesel burner, especially for emergency regeneration under extremely cold operating conditions, e.g., during a short urban drive,
an SCR catalytic converter arranged downstream of the diesel particle filter element with upstream urea injection plus mixing element,
the possibility of cleaning the diesel particle filter element by blowing out the ash particles in the rearward direction via the burner connection after removal of the diesel burner and after opening the blind plug,
embedding of the diesel particle filter element and of the SCR catalytic converter in the muffler absorption material, as a result of which there are no heat losses and a very fast LIGHT OFF system and optimal filter regeneration are achieved,
optimal mixing of the urea by means of a special mixing element, e.g., an inserted flow coil, a semicircular flow loop and/or by means of a mixing nozzle.